1. Field
The present disclosure relates to a compressor, and more particularly, to a discharge opening of a compressor.
2. Background
Generally, a compressor is applied to a vapor compression-type refrigerating cycle (hereinafter a refrigerating cycle) such as a refrigerator or an air conditioner. A compressor may be an inverter type compressor having a controllable rotation speed or a constant speed type compressor having a constant rotation speed.
The compressor can be classified as a hermetic type compressor, where a motor part and a compression part operated by the motor part are installed at an inner space of a hermetic casing, or as an open type compressor, where a motor part is additionally installed outside a casing. In refrigerating devices for home use or business use, the hermetic type compressor is mainly used.
The compressor may be categorized as a rotary compressor or a reciprocating compressor according to the method used to compress a refrigerant. The rotary compressor is a type of compressor that varies a volume of a compression space while a piston performs a rotation motion or an orbital motion in a cylinder. In contrast, the reciprocating compressor is a type of compressor that varies a volume of a compression space while a piston performs a reciprocating motion in a cylinder.
In most compressors, including the rotary compressor and the reciprocating compressor, a large or small dead volume may be created while a refrigerant is sucked, compressed and discharged. In particular, a dead volume created when a refrigerant is discharged from a compression space may greatly affect compressor efficiency. Thus, to achieve optimal compressor efficiency, it is important to minimize the dead volume that may be created when a refrigerant is discharged.
A dead volume of the compressor may be created on a flow path. In particular, a dead volume created while a refrigerant is discharged is closely related to an area and a length of a discharge opening. Thus, it is preferable to optimize the area of the discharge opening, and to minimize the length of the discharge opening, in order to reduce a discharge dead volume of the compressor.
A position and a shape of the discharge opening are also closely related to a discharge dead volume of the compressor. If the discharge opening is disposed at a position far from a compression space, a connection passage for connecting the discharge opening and the compression space with each other can be required, and the connection passage may serve as a dead volume. Thus, it is preferable to reduce a discharge dead volume by avoiding a connection passage by narrowing a distance between the compression space and the discharge opening as much as possible. However, in this instance, it is preferable to obtain a required discharge area by optimizing a shape of the discharge opening.
FIG. 1 is a longitudinal section view of a rotary compressor in accordance with the conventional art, FIG. 2 is a longitudinal section view illustrating a position of a discharge opening of FIG. 1, and FIG. 3 is a planar view illustrating a shape of the discharge opening of FIG. 2.
As shown, in the conventional rotary compressor, a motor part 2 is installed in a compressor casing 1, and a compression part 3 is installed below the motor part 2. The motor part 2 and the compression part 3 are mechanically connected to each other by a crank shaft 23.
The motor part 2 may include a stator 21 forcibly-fixed to the inside of the compressor casing 1, a rotor 22 rotatably-inserted into the stator 21, and a crank shaft 23 coupled to a central part of the rotor 22 by being forcibly-inserted thereinto.
The compression part 3 includes a main bearing 31 and a sub bearing 32 fixed to the compressor casing 1 with a distance therebetween so as to support the crank shaft 23, a cylinder 33 installed between the main bearing 31 and the sub bearing 32 and forming a compression space (S), and a rolling piston 34 coupled to an eccentric portion 23a of the crank shaft 23, and configured to compress a refrigerant while performing an orbital motion in a compression space 33a of the cylinder 33.
A suction opening 33a is penetratingly-formed at the cylinder 33 in a radial direction, and a refrigerant pipe 4 which forms a suction pipe by passing through the compressor casing 1 is connected to the suction opening 33a. A vane slot 33b for slidably inserting a vane 35 is formed at the cylinder 33 at one side of the suction opening 33a in a circumferential direction. A discharge guide groove 33c for guiding a refrigerant to a discharge opening 31a of the main bearing 31 is formed at one side of the vane slot 33b, i.e., a side opposite to the suction opening 33a, as shown in FIG. 2. The discharge guide groove 33c is formed to have an inclined sectional surface so that a sectional area is gradually increased toward an upper surface of the cylinder 33. Thus, as shown in FIG. 3, the discharge opening 31a of the main bearing 31 is formed at an overlapping position with the discharge guide groove 33c, in a perfect circle shape. The discharge guide groove 33c is formed so that about at least 30% of an entire sectional area thereof is positioned outside the compression space (S).
Reference numeral 11 denotes a suction pipe, 12 denotes a discharge pipe, 31b denotes a sealing protrusion, and 36 denotes a discharge valve.
In the conventional rotary compressor, if the rotor 22 of the motor part 2 and the crank shaft 23 are rotated as power is supplied to the motor part 2, a refrigerant is sucked into the compression space (S) of the cylinder 33 as the rolling piston 34 performs an orbital motion. The refrigerant is then repeatedly compressed by the rolling piston 34 and the vane 35, and is discharged to an inner space of the compressor casing 1 through the discharge opening 31a of the main bearing 31.
However, the conventional rotary compressor may have the following problems.
Firstly, the discharge guide groove 33c and the discharge opening 31a serve as a dead volume because a compressed refrigerant remains therein. This may lower compressor efficiency. In particular, the discharge guide groove 33c is configured to guide a refrigerant inside the compression space (S) to the discharge opening 31a. If the discharge guide groove 33c is removed, a proper area of a discharge passage cannot be obtained. This may cause over-compression and discharge loss due to the over-compression. In order to solve such problem, the discharge opening 31a may be moved toward a central part of the cylinder, by a sectional area of the discharge guide groove 33c, in a state where a diameter (D5) of the discharge opening 31a is maintained. However, in this instance, an installation space of a discharge valve is not sufficient, or a shaft accommodation portion of the main bearing is penetrated. This may lower reliability of a bearing.